Absorbent polymer materials, also known as superabsorbent materials, are known in the art for use in absorbent articles such as disposable diapers. The superabsorbent materials can absorb large amounts of fluid, even absorbing more than ten times its weight. Superabsorbent materials are often used in combination with additional materials, particularly fibrous materials, and absorbent article layers, such as a surge layer, which allow for rapid intake of fluids into the absorbent article. These additional materials and layers can act to temporarily hold the fluids until the superabsorbent materials can absorb the relatively large amounts of fluid. Stiff absorbent polymer superabsorbent particles can be used when the absorbent article is under pressure, such as a diaper on an infant, to help maintain an open structure in the absorbent article allowing passage of the fluid to the superabsorbent materials. Therefore it is often desirable that superabsorbent materials include an absorbent polymer having a high stiffness as well as fast absorption properties. In addition, superabsorbent materials desirably have the ability to rapidly absorb fluids from one or more insults from a diaper user.
Current commercial superabsorbent materials typically do not include absorbent polymers having the high stiffness properties as well as fast absorbency rates desired in absorbent articles. There is a need for superabsorbent materials including absorbent polymers having both a high stiffness and a fast fluid absorption rate. There is also a need for a method to modify high stiffness absorbent polymers to increase the absorption rate without unduly reducing the stiffness.